In reinforced concrete construction, it is necessary to support the reinforcing bars (“rebars”) in their designated locations during placement of the concrete and thereafter as it cures. This is accomplished in its most rudimentary form by simply resting the rebar on pieces of concrete placed on the form surface. Obviously, this approach may be unsatisfactory for many reasons, such as the lack of any means for fixing the rebar at their designed positions, as a result of which the rebar may be displaced as the concrete is poured.
In response to the shortcomings of this method of supporting rebar, welded wire supports have been developed and are used extensively in the reinforced concrete construction industry. For example, U.S. Pat. No. 4,689,867 is directed to a welded wire rebar of one type, while U.S. Pat. No. 4,996,816 describes another welded wire rebar support design. With metal supports, however, there is a potential problem of corrosion. Coating the wire with epoxy is a method of dealing with this problem, but coating is expensive, and if the coating is damaged, corrosion may still occur.
Plastic supports are generally non-corrodible and therefore overcome the problems noted above with welded wire supports, but they usually lack the open construction provided by wire supports that permits full flow of concrete through and around the support during concrete placement. While U.S. Pat. Nos. 5,729,949 and 6,089,522 disclose supports that may be formed of plastic and have openings formed in them to facilitate concrete placement, the supports shown in these patents are individual units as opposed to supports that may extend for several spans. U.S. Pat. No. 5,664,390 discloses a plastic bolster that may extend across several spans and uses a pair of spaced legs and a control body that resists deformation through the use of pin-like projections that bite into the underlying surface.